Pawl latch



Oct. 4, 1966 w. DELLITH 3,276,803

PAWL LATCH Filed April 21, 1964 INVENTOR. WERNER DEL L ITH QTTORNEYS United States Patent 3,276,803 PAWL LATCH Werner Dellith, Ringwood, N.J., assignor to Camloc Fastener Corporation, Paramus, N.J., a corporation of New York Fiied Apr. 21, 1964, Ser. No. 361,384 Claims. (Cl. 292-202) My invention relates to a pawl latch and more particularly to an improved pawl latch which is simpler in construction and in operation and less expensive than are pawl latches of the prior art.

There are known in the prior art readily releasable latches for retaining closures over access openings such, for example, as openings in an aircraft cowling. These latches should securely hold the closure in place while at the same time being readily releasable so as to permit rapid access to the interior as desired. Most latches of this type known in the prior art comprises a pawl carried by a threaded bolt or the like and adapted to be moved from an open position to a position behind the frame carrying the closure. After the pawl has been moved to operative position, usually the stud is turned to draw the pawl. into engagement with the frame with the desired force.

While the fasteners described above adequately perform the function of retaining the closure in position, they are relatively complicatedv and are consequently expensive. Moreover, in order to secure the closure in position with the desired force, a number of turns of the bolt or stud must be made during the fastening operation and a corresponding number of turns must be made to release the fastener.

I have invented an improved pawl latch which is simpler in construction and in operation and less expensive than are pawl latches of the prior art. My improved pawl latch provides an automatic clamping or gripping force as the latch moves from its released to its latched position. Only a limited rotary movement is required to provide the clamping force of my latch. The clamping force can readily be adjusted.

One object of my invention is to provide an improved pawl latch which is simpler and less expensive than are pawl latches of the prior act.

Another object of my invention is to provide an improved pawl latch which aifords an automatic clamping force as the latch moves to its latched position.

A further object of my invention is to provide an improved pawl latch requiring only limited rotary movement to clamp two members with a predetermined force.

Still another object of my invention is to provide an improved pawl latch providing a readily adjustable automatic clamping force thereof.

Other and further objects of my invention will appear from the following description.

In general my invention contemplates the provision of an improved pawl latch for securing a closure over a frame access opening in which a shaft supports a spring cam member for rotary movement on the closure from a position out of engagement with the frame to a position at which the cam spring resiliently engages the frame to hold the closure over the opening with a predetermined clamping force. I may provide my pawl latch with means for adjusting the clamping forces provided thereby.

In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIGURE 1 is a plan view illustrating one form of my improved pawl latch.

3,276,803 Patented Oct. 4,- 1966 FIGURE 2 is a fragmentary sectional view of the form of my improved pawl latch shown in FIGURE 1.

FIGURE 3 is a fragmentary plan view of my improved pawl latch taken along the line 3-3 of FIGURE 2.

FIGURE 4 is a'perspective view of an alternate form of my improved pawl latch.

Referring now to FIGURES l to 3 of the drawings, the form of my pawl latch, indicated generally by the reference character 10, shown therein is adapted to secure a panel 12 in position over an opening 14 in a frame 16 which may form part of an aircraft fuselage or the like. Frame 16 has a recess 18 around the opening 14 for the reception of the panel 12. A bracket 20 secured to the panel 12 by any suitable means, such as by rivets 22, has a lip 24 adapted to slide over one side of the opening 14 as the panel is positioned in the recess 18. It will readily be appreciated that rather than employing the bracket 20 along the side of the panel 12, I could, if desired, connect the panel 12 and the frame 16 by means of a hinge extending along that edge.

I provide the panel 12 with an opening 26 which receives a bolt 28 having a head 30 formed with a tool receiving recess 32 into which a tool, such as an Allen-head wrench, can be inserted to turn the bolt 28. I may dispose a decorative washer 34 between the panel '12 and the head 30.

The form of my pawl latch illustrated in FIGURES l to 3 includes a cam spring indicated generally by the reference character 36 formed from a suitable resilient material such as high carbon steel wire. The cam spring 36 has a turn 38 thereon surrounding the shank of the bolt 28. A leg 40 of the cam spring extends from the turn 38 through a slot 42 formed in a flange 44 on a stop washer 46. The leg 40 leads to a bent cam portion 48 of the cam spring 36. A second leg 50 at the end of the cam portion 48 extends through a slot 52 in the bolt 28 and is retained in the slot by a nut 54. I may if desired form the side of the nut 54 in engagement with leg 50 with serrations 56 for receiving the spring leg or I may employ a plain nut.

From the structure just described, it will be apparent that if the bolt 28 is rotated both the washer 46 and the cam spring 36 will turn with the bolt. In one rotary position of the parts illustrated in full lines in FIGURE 1, the cam spring 36 is out of engagement with the frame 16 and a stop 58 on the washer 46 is in engagement with the latch edge of the opening 14. In this relative position of the parts, the panel 12 can be removed from the frame 16. It will be noted that the stop 58 is bent slightlyout of the plane of the washer 46. This feature of the stop prevents the washer from sliding beyond the edge of the opening in the event that the parts 12 and 16 are slightly warped.

From the position of the parts just described, with the panel 12 in position within the opening, the bolt 28 can be turned in a counterclockwise direction as viewed in FIGURE 1. In the course of this movement, the cam portion of spring 48 engages the frame 16 and exerts a clamping force thereon. Ultimately, a stop 60 or the flange 44 engages the edge of opening 14 and the latch is in its locked condition. It will readily be understood that the force with which the cam spring' 36 engages the frame 16 can be regulated Within limits by turning the nut 54.

Referring now to FIGURE 4, an alternate embodiment of my improved pawl latch indicated generally by the reference character 62 comprises a bracket having a base 64 secured to the panel 12 by any suitable means, such as by rivets 66. A shaft 68 having a head 70 by means of which the shaft may be turned extends through the panel 12, through the base 64 and through a flange 72 of the bracket so as to be mounted for rotary movement on the bracket. Head 70 is adapted to be engaged by a tool in any suitable manner known to the art.

In this form of my invention a cam spring indicated generally by the reference character 74 has a first leg 76 extending through an opening in shaft 68 above the flange 72 as viewed in FIGURE 4. Cam spring 74 extends from leg 76 downwardly to a pawl portion 78 and around the shaft 68 in the form of a plurality of coils 80 which'tend normally to expand so as to exert a force in the direction of the axis of shaft 68 between the flange 72 and the pawl portion 78. In the position shown in FIGURE 4, the cam spring 74 is in its latched position in which the pawl portion 78 resiliently engages the frame 16. In this position, movement of the spring in its latching direction is limited by a stop lug 82 carried by the base 64. To remove the panel 12, shaft 68 is rotated in a clockwise direction as viewed in FIGURE 4 until the latch portion 78 comes into engagement with an edge of the bracket.

In operation of the form of my latch shown in FIG- URES 1 to 3, with the parts in full line position, the panel 12 may readily be removed. When it is desired to close the panel, the bolt 28 is turned in a counterclockwise direction as viewed in FIGURE 1 to move the cam portion 48 of the spring into engagement with the frame 16. As the cam spring 36 moves to a position at which the panel 12 is locked, the cam portion 48 exerts a clamping force on the frame 16.

It will be seen that I have accomplished the objects of my invention. I have provided an improved pawl latch which is simple and inexpensive. It automatically exerts a clamping force as it is moved to latching position. Only a relatively small rotary movement is required to produce the clamping action. The clamping force can readily be adjusted.

It will be understood that certain features" and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Having thus described my invention, what I claim is:

l. A fastener for holding two members in assembled relationship including in combination a shaft having a head and having an opening in its end remote from said head, said shaft being rotatably supported on one of said members, a latch formed from a unitary length of resilient material comprising a loop around said shaft, a first leg extending from said loop, a cam portion extending from said leg and a second leg extending from said cam portion, said second leg being disposed in said opening whereby said latch rotates with said shaft from a first position at which said cam portion is out of engagement with the other member to a second position at which said cam portion engages said other member, and a stop washer rotatably carried by said shaft and shaped for engagement by said first leg whereby said stop Washer moves with said latch to. engage said other member to arrest said latch in the second position thereof.

2. A fastener as in claim 1 in which said stop washer has a first upstanding portion, adapted to be engaged by said first leg, for engaging said other member in the second position of said latch and a second portion for engaging said other member in the first position of said latch.

3. A fastener for securing two members in assembled relationship including in combination, a shaft rotatably supported on one of said members for movement around an axis, a latch formed froma unitary length of resilient material, said length comprising a first leg portion extending generally radially from said shaft at a first location around said axle, a second leg portion extending generally radially from said shaft at a second location spaced .around said axis from. said first location, means connecting said first leg portion to said shaft 'at a location axially spaced from said second leg portion .while permitting axial movement of said first leg portion relative to said shaft and a cam portion connecting the ends of said leg portion remote from said shaft, said cam portion adapted resiliently to engage the other member in response to rotation of said shaft.

4. A fastener as in claim 3 wherein said second leg portion is remote from said other member, and including means for securing said remote leg portion to said shaft.

5. A fastener as in claim 4 in which said means for securing said remote leg to said shaftincludes means for adjusting the position of said remote leg along said shaft axis to regulate the force with which said cam portion engages said other member.

References Cited by the Examiner UNITED STATES PATENTS 1,066,495 7/1913 Helvig et a1. 292202 1,163,838 12/1915 Maul 292204 1,943,927 1/ 1934 Phillips 292-202 X 2,309,785 2/1943 Porter et a1 292202 FOREIGN PATENTS 363,169 4/1906 France. 196,101 6/1907 Germany.

EDWARD C. ALLEN, Primary Examiner.

WILLIAM FELDMAN, JOSEPH D. *SEERS,

Examiners.

E. SIMONSEN, R. E. MOORE, Assistant Examiners. 

3. A FASTENER FOR SECURING TWO MEMBERS IN ASSEMBLED RELATIONSHIP INCLUDING IN COMBINATION, A SHAFT ROTATABLY SUPPORTED ON ONE OF SAID MEMBERS FOR MOVEMENT AROUND AN AXIS, A LATCH FORMED FROM A UNITARY LENGTH OF RESILIENT MATERIAL, SAID LENGTH COMPRISING A FIRST LEG PORTION EXTENDING GENERALLY RADIALLY FROM SAID SHAFT AT A FIRST LOCAATION AROUND SAID AXLE, A SECOND LEG PORTION EXTENDING GENERALLY RADIALLY FROM SAID SHAFT AT A SECOND LOCATION SPACED AROUND SAID AXIS FROM SAID FIRST LOCATION, MEANS CONNECTING SAID FIRST LEG PORTION TO SAID SHAFT AT A LOCATION AXIALLY SPACED FROM SAID SECOND LEG PORTION WHILE PERMITTING AXIAL MOVEMENT OF SAID FIRST PORTION RELATIVE TO SAID SHAFT AND A CAM PORTION CONNECTING THE ENDS OF SAID LEG PORTION REMOTE FROM SAID SHAFT, SAID CAM PORTION ADAPTED RESILIENTLY TO ENGAGE THE OTHER MEMBERS IN RESPONSE TO ROTATION OF SAID SHAFT. 